JP5229343B2 - Connection abnormality detection method, network system, and master device - Google Patents

Abstract

There is provided a technique for detecting a connection abnormality of a slave device, in a network system including a master device and slave devices. A connection abnormality detection method of the present invention is a connection abnormality detection method in a network system including a master device and a plurality of slave devices. In the network system, data is transmitted from the master device and then is returned to the master device through the respective slave devices. Each slave device has an upstream-side port and a downstream-side port. The connection abnormality detection method includes a step of acquiring topology information of the network system, a step of closing or opening the port of each slave device such that a serial topology is formed to include a target slave device located on the downmost stream side, a step of transmitting inspection data after the control of the port, and a step of detecting a connection abnormality of the device on the basis of a status of return of the inspection data.

Description

  The present invention relates to a connection abnormality detection method, a network system, and a master device in a network system having a master device and a slave device.

  In the field of FA (Factory Automation), various types of devices share the work process and control. In order to operate various controllers, remote I / Os, and manufacturing equipment used in work in certain areas such as factory facilities in cooperation, an industrial network system called a field network that connects these devices has been constructed. Yes.

In many industrial network systems, various slave devices that collect and control data in production facilities installed in factories and a master device that centrally manages multiple slave devices are connected and communicated to perform production processes. Be controlled.
A network having a master device and a slave device can take various topologies such as a serial shape, a ring shape, a tree shape, or a star shape depending on the cooperation between devices and the convenience of wiring.

  In the serial topology, all slave devices are included in one transmission line starting from the master device. Assuming that the master device is upstream, the information signal flowing from the upstream side to the transmission line passes through the slave devices connected in series one after another and reaches the slave device at the most downstream side. Thereafter, the information signal is sent back from the most downstream side and returns to the master device. In the ring topology, the master device has two ports, that is, the information signal transmission side and the reception side, and the transmitted information signals pass through the slave devices one after another and then from the reception side port. Come back. As described above, in the serial topology and the ring topology, the information signal passes through one transmission path without branching.

  On the other hand, in the tree-like or star-like topology, the route from the master device is branched. As a network device, a hub device having one port connected to the upstream side and a plurality of ports connecting slave devices to the downstream side is arranged as a network device. Alternatively, the slave device itself may directly connect a plurality of other slave devices.

  As an example of an industrial network system for the field of FA, development of a technology called industrial Ethernet to which the Ethernet (registered trademark) technology is applied is progressing. Industrial Ethernet is also called industrial Ethernet or real-time Ethernet, and is a network in which Ethernet technology and equipment are introduced into the FA field at various layers. Various organizations have established and published open standards as industrial Ethernet, and EtherCAT (Ethernet for Control Technology: registered trademark) promoted by ETG (EtherCAT Technology Group) is one of them.

The EtherCAT standard also supports the various topologies described above, and it is possible to combine a series connection using a daisy chain and a branch using a hub device. In EtherCAT, an information signal transmitted from a master device does not reach only a specific destination, but the same signal is used by all slave devices. Since the control signal for each slave device is included in the information signal, the slave device reads the part targeted for itself from the signal, rewrites it as necessary, and passes it to the downstream slave device . Therefore, since the information signal reaches the most downstream without staying at one place in the network, high-speed communication without data collision can be realized.

  As described above, the information signal in EtherCAT travels in the network along a path like a one-stroke stroke. Such characteristics do not change even in a topology including a branch point. That is, when the information signal transmitted from the master device reaches the hub device which is a branching point, a predetermined port is selected from a plurality of ports and transmitted to the slave device connected thereto. When there are other slave devices downstream of the slave device, the information signals are sequentially transferred, and after reaching the most downstream, are returned to the hub device. Subsequently, the data is transmitted to a slave device connected to another port included in the hub device.

  Japanese Unexamined Patent Application Publication No. 2008-124791 (Patent Document 1) describes a network failure monitoring method for detecting a cable connection error or a setting error in Ethernet. Japanese Unexamined Patent Application Publication No. 2010-034876 (Patent Document 2) describes a method of detecting a failure occurrence in a network relay device or a communication line and specifying a failure occurrence location. However, none of the documents describes a method for detecting a connection abnormality in an industrial network system in which a master device and a slave device communicate with each other.

JP 2008-124791 A JP 2010-034876 A

  In the industrial network system constructed in accordance with the above-mentioned EtherCAT standard, there is a problem that it is difficult to detect a location where a connection abnormality such as a cable failure occurs between a master device and a slave device. . For this reason, there is a possibility that it takes time to recover from the failure as compared with the standard Ethernet standard in which various means for detecting the failure are prepared. This problem will be described below.

  FIG. 2A shows a state where five nodes N1 to N5 are hub-connected in accordance with a general Ethernet standard. Here, it is assumed that an abnormality has occurred in the cable connecting node N4 to the hub. There is a method of checking whether communication is established individually by specifying a node in the network in order to detect whether or not a failure has occurred in communication with other nodes from the user node N1. . In this case, a function such as a ping command that transmits a packet to the partner node and requests a reply may be used. When there is no reply from the node N4, it can be detected that a failure has occurred. In addition, early failure detection can be realized by providing a mechanism for mutual monitoring between nodes.

  FIG. 2B shows a network configuration according to the EtherCAT standard, in which a master device M and four slave devices S1 to S4 are connected in a series topology. Here, the information signal sent from the master device passes through all the slaves as circled numbers 1 to 4 and is sequentially delivered downstream. Then, after reaching the slave S4, it follows the reverse path and returns to the master device. Therefore, for example, even if the information signal does not return to the master device due to a cable failure between the slaves S3 and S4, the master device cannot know where in the path the failure has occurred.

When the location where a failure has occurred cannot be detected from the master device, it is necessary to check the connection locations one by one in order to isolate the problem, which takes a lot of time. If the problem is too much for the user, inspection by a customer engineer is required, which may further increase the time and cost required for recovery.

  Since EtherCAT has a feature that the information signal takes a one-stroke path as described above, if the slave device in the network is not correctly connected, the information signal is not correctly passed in the network, which is expected. Control will not be possible. An incorrect connection is, for example, a state in which the quality of the cable is poor and a part or all of the communication is lost, or an incorrect type of port is selected when the cable is inserted into the port of the slave device. Therefore, the failure to detect the failure occurrence point at an early stage leads to erroneous control in the production process, resulting in obstructing the stable operation of the entire network and reducing usability.

  Some EtherCAT vendors may provide a mechanism for handling connection errors. For example, when the information signal does not return within a certain time, the information signal is sent again to improve the communication quality of the entire system. However, this method cannot be said to have essentially solved the failure, and it cannot detect where in the network the failure has occurred. Furthermore, since a certain communication resource is consumed by retransmitting the information signal, there is a risk of compressing the network bandwidth.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a technique for detecting a connection abnormality of a slave device in a network system having a master device and a slave device. .

  In order to achieve the above object, the present invention adopts the following first configuration. That is, a network system that includes a master device and a plurality of slave devices, and data transmitted from the master device is returned to the master device after sequentially passing from the most upstream slave device to the most downstream slave device. In this connection abnormality detection method, each slave device has a plurality of ports including an upstream port for connecting to an upstream device and at least one downstream port for connecting to a downstream device. The connection abnormality detection method includes a step in which the master device acquires topology information that is a topology of the network system, and the master device determines that the target slave device to be inspected is the most downstream based on the topology information. And the serial topology from the master device to the target slave device A port control step for switching between blocking and opening of the port of each slave device; a step in which the master device transmits inspection data after the port control step; and a step in which the master device transmits the inspection data. And detecting a connection abnormality of the target slave device based on the return status of the connection slave.

  According to such a connection abnormality detection method, even in a network system in which data transmitted from a master device passes through all slave devices included in the topology, data for inspection is transmitted / received after the target slave device is identified. You can check whether there is a connection error. As a result, it is possible to easily identify the location where the abnormality has occurred and notify the user, so that it is possible to quickly respond to the failure.

  The present invention can also employ the following second configuration. That is, if no connection abnormality of the target slave device is detected in the detecting step, the master device sets the slave device connected to the downstream port of the target slave device as a new target slave device, and It can be configured to execute the port control step.

  According to such a connection abnormality detection method, it is possible to inspect the slave devices included in the network system one by one from the upstream device toward the downstream side. Therefore, the inspected portion can be expanded little by little. Therefore, if a connection abnormality is detected when trying to detect again, it is possible to clarify that the newly expanded part to be inspected is the cause of the abnormality, contributing to the rapid identification of the location of the failure. it can.

  The present invention can also employ the following third configuration. That is, when the topology of the network system includes a branch point, in the port control step, the master device can be configured to select one of the branch destinations to form a serial topology.

  According to such a connection abnormality detection method, even when there is a branch location, a serial topology is selected by selecting one branch destination to enable communication between the master device and the slave device and blocking the other branch destination. Can be formed. If there is no connection abnormality at the selected branch destination, all the slave devices included in the network system can be inspected by changing the branch destination in order.

  The present invention can also employ the following fourth configuration. That is, the plurality of slave devices are connected by a cable, and in the transmitting step, the master device performs a plurality of inspection data transmissions to the target slave device, and in the detecting step, the master device If the number of times the returned inspection data can be received is smaller than the number of times the inspection data is transmitted in the transmitting step, the cable connecting the target slave device is abnormal. Can take the configuration.

  According to such a connection abnormality detection method, it is possible to check whether there is a failure in the cable connecting the slave device by inspecting the number of inspection data transmitted to the slave device that does not return. It becomes possible.

  The present invention can also employ the following fifth configuration. That is, the topology information acquired by the master device in the acquiring step includes a position address determined based on the order in which each slave device is connected and the type of port used for connection between the slave devices. The inspection data transmitted by the master device in the transmitting step is data for confirming the number of slave devices included in the serial topology formed in the port control step, and in the detecting step, The master device, when the expected value of the number of devices to the target slave device obtained from the topology information and the position address does not match the number of devices confirmed by the returned inspection data, The upstream and downstream ports of the device It can be configured as assumed that there is connection error be mistaken bets.

  According to such a connection abnormality detection method, it is possible to detect that a position address has been erroneously assigned due to the mistake of the upstream port and the downstream port of the slave device, so the location where there was a connection abnormality from the master device Can be specified.

The present invention can also employ the following sixth configuration. That is, in the fifth configuration, when the target slave device is a slave device located at the most downstream side of the network system, the topology information acquired by the master device in the acquiring step is obtained for each port of the slave device. In the detecting step, the master device includes the target device when the other device is connected only to the upstream port among the ports of the target slave device. A configuration can be adopted in which there is a connection abnormality in which the upstream port and the downstream port of the slave device are mistaken.

  According to such a connection abnormality detection method, depending on the fifth configuration, even when a connection abnormality cannot be obtained by comparing the expected number of devices up to the target slave device with the number confirmed by the inspection data. Thus, it becomes possible to detect a mistake between the upstream port and the downstream port.

  The present invention can also employ the following seventh configuration. That is, the network system is composed of a master device and a plurality of slave devices, and the data transmitted from the master device is returned to the master device after sequentially passing from the most upstream slave device to the most downstream slave device. Each slave device has a plurality of ports including an upstream port for connecting to an upstream device and at least one downstream port for connecting to a downstream device, the master device comprising: Means for acquiring topology information that is a topology of the network system, and based on the topology information, the target slave device to be inspected is the most downstream, and the topology from the master device to the target slave device is a serial topology Port control means to switch the blocking and opening of each slave device port A transmission / reception means for transmitting inspection data after the control by the port control means and receiving the inspection data returned, and the target slave device based on a return status of the inspection data And a determination means for detecting an abnormal connection.

  Even with such a network system, it is possible to easily identify a location where an abnormality has occurred and notify the user, so that it is possible to quickly respond to a failure.

  The present invention can also employ the following eighth configuration. That is, it is composed of a master device and a plurality of slave devices, and the data transmitted from the master device is returned to the master device after sequentially passing from the most upstream slave device to the most downstream slave device. The device is a master device in a network system having a plurality of ports including an upstream port for connecting to an upstream device and at least one downstream port for connecting to a downstream device, Obtaining topology information that is the topology of the network system, and based on the topology information, the target slave device to be inspected is the most downstream, and the topology from the master device to the target slave device is a serial topology. The port control function that switches between blocking and opening the port of each slave device And transmitting and receiving inspection data after being controlled by the port control means, and receiving and receiving the inspection data, and the target slave based on the return status of the inspection data And a determination unit that detects a connection abnormality of the device.

  Even with such a master device, it is possible to easily identify a location where an abnormality has occurred and notify the user, so that it is possible to quickly respond to a failure.

  ADVANTAGE OF THE INVENTION According to this invention, the technique which detects the connection abnormality of a slave apparatus can be provided in the network system which has a master apparatus and a slave apparatus.

It is a block diagram explaining the structure of the master apparatus of this invention, and a slave apparatus. It is a figure explaining the difference in transmission of the information signal in Ethernet and EtherCAT. It is a flowchart explaining the whole process of this invention. It is a figure explaining the port control in Example 1 of this invention. It is a flowchart explaining the process of the test mode in Example 1 of this invention. It is a figure explaining the port control in Example 2 of this invention. It is a figure explaining the process in Example 3 of this invention. It is a flowchart explaining the process of the test mode in Example 3 of this invention. It is a figure explaining the process in Example 4 of this invention. It is a block diagram explaining the structural example of an industrial network system. It is a figure explaining the process in Example 5 of this invention. It is a flowchart explaining the process of the test mode in Example 5 of this invention.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the following embodiment, a system construction method conforming to the EtherCAT standard is taken up, but the subject of the present invention is not limited to this. The present invention can be applied to any industrial network system that has a master device and a slave device and takes a path in which an information signal transmitted from the master device returns via each slave device. .

(Configuration of industrial network system)
First, a configuration example of an industrial network system targeted by the present invention will be described with reference to FIG. In this figure, an industrial network system 100 includes a master device 200 (PLC: Programmable Logic Controller) and a plurality of slave devices 300 directly via a cable 400, an I / O unit 500 provided in the device, and a hub device 700. Alternatively, it is formed by being indirectly connected. The slave device 300 includes a power supply unit, a motor unit, a counter unit, an image unit, a communication unit, an I / O unit, and the like. The master device 200 may be connected to a management device 600 for the user to perform operation settings of the master device 200, display of the operation status of the industrial network system 100, network design, and the like. The management apparatus 600 is configured by a personal computer installed with a setting tool.

The hub device 700 has one port 701 connected to the upstream side and a plurality of ports 702a to 702c connected to the downstream side when the master device side is the upstream side. A user can create a desired topology by connecting each device using a cable or a hub device while setting the order or branching. The branch structure can be created not only by the hub device but also by connecting a plurality of slave devices downstream from the slave device.
In EtherCAT, it is possible to divert the cable 400 that is used in the general Ethernet standard, or to manufacture it in an Ethernet equipment manufacturing facility. This realizes cost reduction.

  The industrial network system 100 is a network conforming to the EtherCAT standard, and is installed in a factory or the like and used as an FA system. The master device 200 transmits an information signal including control data through a network according to programs and operations. As a response to the request from the master device included in the information signal, the slave device 300 performs device operation based on the received information signal, and rewrite and return processing of the received information signal. Production in a factory including the industrial network system 100 is achieved by the master device controlling the contents and timing of the operation so that the slave device as a whole works together to share the work.

In standards such as Ethernet, the arrangement order of devices in a network is not particularly limited. This is because each device has a unique physical address, such as a mac address, that is assigned regardless of its location in the network.

  On the other hand, in the EtherCAT standard, the position of the device on the network based on the connection order is meaningful for information transmission between the master device and the slave device. This is because the slave device does not have an absolute address such as a mac address, and the master device assigns the address (node address) of each slave device based on the position (position address) in the network. The information signal sent out by the master device is intended for all slave devices, and each slave device reads / writes information at a position corresponding to its own address. Therefore, when the wiring order of the slave devices arranged in series is different from the information designed by the design support system, a slave different from the one assumed by the master device reads and writes information signals. As a result, there may be a situation in which the operation of the motor or the like becomes abnormal because the control data for the slave device is incorrect, or a situation where the information signal is overwritten by an erroneous slave and the consistency cannot be obtained.

<Example 1>
In the present embodiment, a description will be given of a method of detecting a failure location by control from a master device when a cable failure occurs as a connection error of a slave device in a network constructed in accordance with the EtherCAT standard.

(Device configuration)
FIG. 1 is a block diagram illustrating a configuration of a master device and a slave device according to the present embodiment. The master device 200 includes a topology acquisition unit 201, a port control unit 202, a transmission / reception unit 203, a determination unit 204, a control unit 205, and a port 206.

  The topology acquisition unit 201 collects information by communicating with all slave devices connected to the downstream side of the master device. Details of the information to be collected will be described later. Then, the current topology is interpreted based on the collected information. The port control unit 202 instructs each slave device in the network whether to open or block each port. When a port of a certain slave device is cut off, an information signal is not passed to a slave device downstream from that port, so that the network topology changes. In the connection abnormality detection of the present embodiment, the network topology is changed in series, and the slave device located at the most downstream side of the series topology is set as the target slave device. Then, the quality of the cable connecting the target slave device to the upstream side is inspected.

  The transmission / reception means 203 of the master device manages transmission / reception of information signals to / from the slave device. Particularly in the test mode, the information signal is transmitted a plurality of times, and the ratio of the returned information signal is obtained. The determination unit 204 determines whether or not there is a connection abnormality in the target slave device based on the current topology constructed by the port open / close control of the port control unit and the rate at which the transmission / reception unit has successfully received the information signal. judge.

  The control unit 205 is a CPU or the like that executes a program, and controls each block of the master device via a control line (not shown). The port 206 sends the information signal from the master device to the downstream slave device and receives the information signal returned from the slave device. Different ports may be used for sending and receiving information signals.

The slave device 300 includes a transmission / reception unit 301, a control unit 302, an upstream port 303a (IN port), and a downstream port 303b (OUT port). The transmission / reception means 301 of the slave device receives the information signal from the upstream side, reads the information from the position targeted for the slave device, and rewrites it as necessary. The control unit 302 includes a CPU and the like as in the master device, and performs control via a control line (not shown). There is only one upstream port 303a in the slave device. On the other hand, a plurality of downstream ports 303b may exist in the slave device.
Although only one slave device is described in this figure, actually, a slave device having the same configuration as that shown in this figure is connected to the downstream side of the port 303b in a topology desired by the user.

  When designing a network in accordance with the EtherCAT standard, it is necessary to perform a design that takes into account the topology such as the connection order between slave devices and the port number of the hub device. However, normal users do not always have expertise and experience like SE and customer engineers. Therefore, it is preferable to provide a design support system for helping the design work by making the topology easy to understand by graphical display. The design support system is provided as a management device connected to the master device. The management device is a personal computer installed with a setting tool that is an application for creating setting information. A user can perform an easy design by performing an operation using an input device such as a keyboard or a mouse from a GUI displayed on the display of the management device.

(Overall processing flow)
First, the processing flow of the entire embodiment will be described with reference to FIG. In step S301, the power of the master device is turned on, and in step S302, online connection to the network is made. Then, the transmission / reception means 201 of the master device communicates with each slave device in the network via the port 206 as an initial process at start-up or according to an explicit operation of the user, and collects information on the slave device. And save (step S303). At this time, access is performed with an address determined according to the position of the slave device on the wiring. The information obtained at this time includes the name of the device, the number of OUT ports, the status of blocking and opening, the name of the connection destination device for each port, and the like.

In step S304, the master device topology acquisition unit 201 interprets the network topology. That is, since the information acquired in step S303 is information indicating a structure in which slave devices are connected via ports, the topology is interpreted by matching the information obtained from all slave devices and analyzing the information with a predetermined algorithm. it can. If the topology information is already stored in the master device, steps S303 and S304 are not performed, and the test mode can be entered immediately.
Step S305 is a test mode that characterizes this embodiment. Details of this processing will be described later with reference to another flowchart. In the test mode, whether there is a connection abnormality such as a cable failure in the network, and if there is an abnormality, the occurrence location is detected.

  When there is a connection abnormality (step S306 = YES), the user is notified by some means such as display on the screen of the management apparatus, sound, LED lighting (step S307). For example, it is preferable to display the location of the failure on the topology diagram of the network graphically displayed on the display of the management device in order to help the user understand. Since the user who is notified of the abnormality can know the location where the failure has occurred, it is possible to respond quickly without requiring time to isolate the problem.

(Test mode processing flow)
Next, the processing flow from the start to the end of the test mode for detecting connection abnormality will be described in more detail with reference to FIG. As needed, the schematic diagram of the topology of the industrial network system shown in FIG. 4 is also referred to. At the start of the flow process, the master device and the slave device are connected with the power turned on. The test mode is a dedicated mode for detecting a connection abnormality, unlike a production process using an industrial network system. The transition to the test mode is performed by an explicit action by the user, for example, an input from a GUI on the management apparatus connected to the master apparatus, or an operation of a physical switch or button. Alternatively, the test mode may be shifted when the information signal is interrupted. A series of processing after entering the test mode may be automatically performed by the control means to display the result, or the user may perform step by step while checking the situation.

In step S501, the industrial network system shifts to the test mode. As a result, the control by the normal information signal shifts to the cable connection confirmation.
In step S502, a target slave device whose connection status is to be confirmed is determined. One target slave device is selected from the network. In this embodiment, in particular, in consideration of the nature of EtherCAT, target slave devices are selected in order from the upstream side of the network. FIGS. 4A to 4D show the state of processing in time series, and are selected in the order of slave devices S1 to S4.

In step S503, when the port control unit 202 of the master device instructs to shut off and open the port of each slave device, a serial topology up to the target slave device is formed. For example, in FIG. 4A, the downstream port of the slave device S1 selected as the target slave device is blocked. Thereby, a serial topology composed of the master device and the slave device S1 is formed.
In step S504, the transmission / reception means 203 of the master device makes multiple attempts to transmit the information signal to the target slave device and receive the returned information signal. The number of times of information transmission / reception is arbitrary. In this embodiment, for example, it is 100. Then, the transmission / reception means 203 of the master device obtains the number of times of successful reception with respect to the number of times of transmission (step S505).

  If the number of successful receptions is 100, it can be determined that there is no abnormality in the connection to the target slave device (here, S1) (step S507). On the other hand, if the number of successes is less than 100, it is determined that there is an abnormality in the connection to the target slave device (step S506). If it is determined that there is an abnormality, as described in the overall processing flow, the user is notified of the location of the failure and encouraged to respond. An information signal transmitted a plurality of times becomes inspection data in this embodiment.

  If all the slave devices included in the network have not been checked (step S508 = NO), the process returns to the target slave device determination (S503) and the processing is continued. The slave device selection at that time is shown in FIG. In this case, in order to extend the topology formed in FIG. 4A, the slave device S2 that is one downstream from the current target slave device S1 is selected. Then, the downstream port of the target slave device S1 in the previous process is opened, the downstream port of the new target slave device S2 is blocked, and information signal transmission / reception is performed a plurality of times. If the number of transmissions and the number of receptions match, it is determined that there is no connection abnormality related to the slave device S2.

At this time, it is determined that there is no abnormality between the slave devices S1 and S2 as well as between the master device and the slave device S1 that have already been determined to be normal. In this way, by detecting the abnormality sequentially from the upstream side, the inspected section can be extended.
Subsequently, in FIG. 4C, similarly, the slave device S3 becomes a new target slave device, the downstream port is blocked, and it is checked whether there is a problem in information signal transmission / reception multiple times.

When the target slave device moves to S4, it is assumed that the number of transmissions and the number of receptions do not match in the determination in step S505. There may be a case where only a part of the information signal does not return and a case where reception is completely interrupted. In either case, it can be determined that some kind of connection abnormality has occurred, and there is a possibility that the severity of the abnormality can be determined by the proportion of information signals that do not return.
In this case, since it is known that there is no abnormality between the master device and the slave device S1, between the slave devices S1 and S2, and between the slave devices S2 and S3, the slave device S3 newly added to the serial topology It can be seen that an abnormality has occurred in the cable during S4.

  In this way, even in an industrial network system in which communication specifying individual slave devices cannot be performed and an information signal passes through all slave devices, the location where a failure has occurred can be specified from the master device side. By conveying this information to the user, it is possible to contribute to quick recovery from a failure. Therefore, even a user who does not have specialized knowledge can cope with a failure, and a network in consideration of high stability and improvement of usability can be provided.

<Example 2>
In the present embodiment, a method of forming a serial topology when a network includes a branch location such as a hub device or a slave device having a plurality of downstream ports will be described. By this method, the connection abnormality detection method as in the first embodiment can be applied to networks of various topologies.

FIG. 6 is a diagram for explaining the topology formation of this embodiment.
FIG. 6A shows the first process after the detection process starts. In step S502 in the flow of FIG. 5, the slave device S1 is determined as the target slave device. In S503, the downstream port of the slave device S1 is shut off, the upstream port is opened, and the topology becomes serial.

  If there is no cable fault in the formed serial topology, the process proceeds to the second step S502 through a loop in the flow. This state is shown in FIG. Here, the slave device S2 is the target slave device. Another slave device is connected to the two downstream ports of the slave device S2, which becomes a branch point. By blocking both ports, a serial topology from the master device to the slave device S2 can be formed.

  If no connection abnormality has been confirmed so far, as shown in FIG. 6C, the slave device S3 at one branch destination is selected as the target slave device. Only the port on the side connected to S3 in the slave device S2 is opened, and the port on the side connected to the slave device S5 is blocked. Here, when there is a failure in the cable between the slave devices S2 and S3, the number of times of transmission and reception of the information signal sent from the master device does not match. It can be detected.

  On the other hand, if no abnormality is found even after the inspection from the slave device S3 up to S4, the operation proceeds to another branch destination inspection. For this purpose, of the two ports of the slave device S2, the port on the slave device S3 side is blocked and the port on the slave device S5 side is opened.

  In a network according to the EtherCAT standard, various topologies including branch points are assumed. However, even in a network with branches, according to the method of this embodiment, the slave devices are identified in order from the upstream side for each branch, and instructions are given by the port control means to know the location of the failure. Can do.

<Example 3>
In the present embodiment, the connection abnormality to be detected is a port misconnection in which the types of ports when connecting slave devices are mistaken. In particular, when a cable is connected to the target slave device from the upstream side, a case where the cable is originally inserted into the IN port of the target slave device but is accidentally inserted into the OUT port will be taken up. Since the OUT port of the upstream slave device and the OUT port of the target slave device are connected by a cable, such an erroneous connection is also referred to as an OUT-OUT connection.

With reference to FIG. 7, a problem when there is an OUT-OUT connection will be described. Here, for simplification, a serial topology including one master device M and four slave devices S1 to S4 is examined. First, FIG. 7A shows a state in which the IN port and OUT port of each device are normally connected.
At this time, an address (position address) based on the position is assigned to the slave device in the network. For example, when the address number is increased from the upstream side, the position address is assigned as slave device S1 = 1, slave device S2 = 2, and so on. The position address setting rule shown here is merely an example, and can be changed as appropriate for each industrial Ethernet standard to which the present invention is applied.

  On the other hand, FIG. 7B is a schematic diagram when there is an OUT-OUT connection. That is, the cable extending from the OUT port of the slave device S1 is erroneously connected to the OUT port, not the IN port of the slave device S2. Therefore, the IN port of the slave device S2 is connected to the downstream slave device S3. The position address at this time is the same as that in FIG. 7A for the slave device S1 = 1, but the number is different from that in FIG. 7A downstream from the slave device S2 in which there is an erroneous connection.

  The position address is assigned in this way because of the EtherCAT standard. This will be described with reference to FIG. The position address of each slave device is determined based on the order in which the information signals sent from the master device are processed. Since the slave device performs various processes for the information signal delivered from the IN port, the position addresses are assigned in the order of the circled numbers 1 to 4.

  As described above, the erroneous connection of the ports causes the position address to be erroneously assigned. As a result, the actual position address differs from the assumption when the master device sets control data for each slave device in the information signal. For this reason, a method for easily detecting the OUT-OUT connection is required in order to prevent unintended data transfer and unintentional overwriting that may occur.

(Processing flow)
The processing flow of the present embodiment will be described with reference to FIG. The topology shown in FIG. 7 is also referred to as necessary. The conditions at the time of starting the flow process are the same as those in the first embodiment, and the process is started from the point of entering the erroneous connection test mode. For comparison, the behavior when the inspection method of this embodiment is applied to each of the normal connection in FIG. 7A and the erroneous connection in FIG. 7B will be examined.

In steps S801 to S803, processing similar to that in steps S501 to S503 in FIG. 5 is performed. That is, the process shifts to the test mode in step S801, and the target slave device is determined in step S802. The target slave devices are selected in order from the upstream side of the network as in the first embodiment.
In step S803, blocking or opening for each port of each slave device is determined by an instruction from the port control means of the master device, and a serial topology up to the target slave device is constructed. At this time, the master device uses information obtained by performing topology interpretation in the entire processing flow. Here, it should be noted that the master device issues an instruction by designating the position address of the slave device whose port is to be blocked.

  In step S804, a command for confirming the number of slave devices is thrown by the transmission / reception means 203 of the master device for all slave devices participating in the current network topology. As described above, the information signal in EtherCAT returns to the master device via all slave devices. Therefore, for example, the number of devices can be confirmed by a method in which the slave device receiving the information signal increases a predetermined variable one by one. This information signal is inspection data in this embodiment.

  First, a serial topology in which the master device to the slave device S2 are normally connected as shown in FIG. The master device designates the slave device with the position address = 2 and blocks the OUT port to form a serial topology. At this time, the expected number of slave devices by the master device is two. When the command in step S804 is executed for such a network, the number of devices is determined to be two since the variables are increased by the slave devices S1 and S2. Therefore, step S805 = YES, and it is determined that there is no connection abnormality.

  Next, a serial topology in which the slave devices S1 and S2 are OUT-OUT connected as shown in FIG. As in the above case, the master device designates the slave device with the position address = 2 and blocks the OUT port to form a serial topology. At this time, the expected value of the number of slave devices by the master device is also two as above. On the other hand, when the command in step S804 is executed for such a network, the number of devices is determined to be three because the variables are increased by the slave devices S1, S2, and S3. Therefore, step S805 = NO, and it is determined that there is a connection abnormality.

According to the connection abnormality detection method of the present embodiment, a state in which OUT-OUT connection is established between slave devices by shifting to the test mode and sending a port cutoff and release instruction and command from the master device. Can be detected. For this reason, even if there is an erroneous connection, it is possible to quickly identify the location of the failure from the operation of the management device or the like, so that stable operation of the system and improvement of usability can be realized.
Even if the industrial network system has a topology including a branch, the connection abnormality detection method of this embodiment can be applied by appropriately blocking and opening the port of the slave device.

<Example 4>
In this embodiment, a method for detecting a state in which the end of the industrial network system, that is, the slave device located at the most downstream side is connected OUT-OUT is described. The state of the target slave device of this embodiment is shown in FIG. For simplicity, assume a network in which a master device and slave devices S1 to S4 are connected in series. At this time, the master device to the slave device S3 are normally connected, but the cable extending from the OUT port of the slave device S3 is inserted into the OUT port of the slave device S4, resulting in an erroneous connection.

  As described in the third embodiment, since the position address of each slave device is determined based on the order in which the information signals are processed, the position addresses 1 to 4 are assigned to the slave devices S1 to S4, respectively. In the third embodiment, the expected value of the number of devices in the serial topology constructed by the port control means of the master device is compared with the number of devices confirmed by the command sent from the transmission / reception means of the master device, and OUT− I was trying to detect an OUT connection. However, in the case of the present embodiment, even if the method of the third embodiment is executed with the slave device S4 that is erroneously connected as the target slave device, the connection abnormality cannot be detected because the number of devices matches the expected value.

  If such an erroneous connection state is left unattended, there is a possibility of causing a problem of control data. Furthermore, when the user connects another slave device behind the slave device S4, there is a possibility that the cable is inserted into the open IN port instead of the occupied OUT port. Therefore, a method for detecting the OUT-OUT connection is required even in the case of this embodiment.

  As in this embodiment, regarding the slave device located on the most downstream side of the system, the OUT-OUT connection can be detected by making a determination based on information collected from the slave device by the master device. That is, when the master device collects information on the slave device, the connection status for each port of the slave device is acquired. Thus, if the connection destination device exists only at the OUT port of the slave device S4 in the collected information, it can be determined that the slave devices S3 and S4 are OUT-OUT connected. Alternatively, the master device may collect information again in order to detect connection abnormality of the slave device at the most downstream side of the system.

  According to the connection abnormality detection method of the present embodiment, it is possible to detect the OUT-OUT connection even for the slave device located at the end of the system and prompt the user to respond.

<Example 5>
In this embodiment, the connection abnormality to be detected is a loop connection existing in the network. FIG. 11A shows how the loop connection is performed. In the network shown in the figure, one master device and four slave devices S1 to S4 are connected in series. The slave device S2 has one IN port and two OUT ports. The two OUT ports included in the slave device are referred to as a first OUT port (OUT1 port) and a second OUT port (OUT2 port).

  As illustrated, the IN port of the slave device S3 is connected to the OUT2 port of the slave device S2. The OUT1 port of the slave device S2 is connected to the OUT port of the slave device S4 at the end of the network. A state in which the path between the slave devices S2 to S4 is circulated instead of a normal stroke is called loop connection.

  In the EtherCAT standard, when a slave device has two OUT ports, the context of sending information is determined. In a normal network (not including a loop connection), when an information signal that has entered the slave device from the IN port is sent downstream, it is first output from the OUT1 port and then returns along a one-stroke path. And then output from the OUT2 port.

  A problem that may occur when a loop connection exists in the network will be examined with reference to FIG. The information signal sent from the master device moves along a route indicated by a dotted arrow. That is, after passing through the slave device S1 and reaching the slave device S2, it is transmitted from the OUT1 port having a high priority and enters the slave device S4. Thereafter, the slave devices move in the order of S3, S2, and S1.

  However, at this time, only the slave devices S1 and S2 perform the reception process for the information signal (corresponding to the circled numbers 1 and 2). On the other hand, in the slave devices S3 and S4, the information signal reception process is not performed. This is because the slave device processes only the information signal input from the IN port. As a result, instructions from the master device to the slave devices S3 and S4 cannot be delivered, and network operations such as production processes cannot be performed normally. Therefore, it has been necessary to detect a loop connection in the network.

(Processing flow)
A process for detecting such a loop connection as a connection abnormality will be described with reference to the flowchart of FIG. Here, it is described as one of the test modes in step S305 in FIG. 3, but in practice, loop connection detection can be performed at a desired timing.

In step S1201, the network shifts to the test mode. Subsequently, in step S1202, an expected value of the number of links of the slave devices in the network is obtained. The number of links means the number of ports connected to other devices by cables, and other devices to be connected include the master device. However, the port of the master device is not included in the number of links. The expected value L _{exp of the} number of links is obtained by the following equation (1). Note that S _num is the number of slave devices.
L _exp = ((S _num −1) × 2) +1 (1)

  In step S1203, the actual total number of links of the slave device is obtained. This can be obtained based on the information collected in step S303 in FIG. That is, since the status of the connection destination is known for each port of the slave device, the total number of links can be obtained by summing them.

  In step S1204, the expected number of links is compared with the actual numerical value. If the values are different (S1204 = NO), it is determined that there is a connection abnormality, in this case, there is a loop connection. On the other hand, if the numerical values are the same (S1204 = YES), it is determined that the connection is normal. Returning to step S306 in FIG. 3, the user is notified of the presence of the loop connection by an arbitrary method, and prompts for a response.

(How to find the number of links)
The processing in steps S1202 to S1204 will be specifically described.
First, an expected value of the number of links is obtained with the network configuration as in this embodiment. Since there are four slave devices, applying this to equation (1)
L _exp = ((4-1) × 2) + 1 = 7
Therefore, the expected value is 7.

First, the actual total number of links in a network that does not have loop connection locations will be examined with reference to FIG. In this figure, the cable is connected normally and there is no loop connection. The total number of links at this time is seven, two for each of the slave devices S1, S2, and S3 and one for the slave device S4.
Therefore, the expected value and the actual number of all links are equal, and it is determined that there is no connection abnormality.

Next, consider the case of FIG. 11A with a loop connection. In this case, the number of slave devices is four, but the slave device S3 and S4 connected in a ring does not receive information signals, so the master device is connected to two slave devices. recognize. When there are two slave devices, the expected number of links is three in S1, two in S1 and one in S2. On the other hand, the actual number of links at this time is two for the slave device S1 and three for the slave device S2, for a total of five.
Therefore, the expected value and the actual number of all links do not match, and it is determined that there is a connection abnormality.

As described above, according to the connection abnormality detection method of the present embodiment, the loop connection included in the network can be detected from the master device by verifying the number of links of the slave device in the test mode. When a loop connection is detected, it is possible to prompt an early response to a failure by notifying the user. As a result, it is possible to contribute to correct control of the production process and stable operation.
In this embodiment, the structure in which the master device and the slave device are connected in series is taken up. However, even in a topology having a branch point, the connection number can be determined by comparing the expected number of links with the actual number of all links. Abnormalities can be detected.

  200: Master device 201: Topology acquisition unit 202: Port control unit 203: Transmission / reception unit 204: Determination unit 300: Slave unit 301: Transmission / reception unit 303a: Upstream port 303b: Downstream port

Claims (9)

A connection in a network system, which is composed of a master device and a plurality of slave devices, and data transmitted from the master device is returned to the master device after sequentially passing from the most upstream slave device to the most downstream slave device. An anomaly detection method,
Each slave device has a plurality of ports including an upstream port for connecting to an upstream device and at least one downstream port for connecting to a downstream device;
The connection abnormality detection method is:
The master device acquiring topology information that is a topology of the network system;
Based on the topology information, the master device is configured so that the target slave device to be inspected is the most downstream and the master device to the target slave device has a serial topology. A port control step for switching between blocking and opening; and
The master device transmitting inspection data after the port control step;
The master device detecting a connection abnormality of the target slave device based on a return status of the inspection data; and
Have
When the topology of the network system includes a branch point, in the port control step, the master device selects one of the branch destinations to form a serial topology. Detection method. If no connection abnormality of the target slave device is detected in the detecting step, the master device sets the slave device connected to the downstream port of the target slave device as a new target slave device, and performs the port control. The connection abnormality detection method according to claim 1, wherein the step is executed. The plurality of slave devices are connected by a cable,
In the transmitting step, the master device performs a plurality of inspection data transmissions to the target slave device,
In the detecting step, the master device connects the target slave device when the number of times the returned inspection data can be received is smaller than the number of times the inspection data is transmitted in the transmitting step. connection abnormality detection method according to claim 1 or 2, characterized in that it is assumed that there is an abnormality in. The topology information acquired by the master device in the acquiring step includes a position address determined based on the order in which each slave device is connected and the type of port used for connection between the slave devices,
The inspection data transmitted by the master device in the transmitting step is data for confirming the number of slave devices included in the serial topology formed in the port control step,
In the detecting step, the master device does not match an expected value of the number of devices to the target slave device obtained from the topology information and the position address and the number of devices confirmed by the returned inspection data. 3. The connection abnormality detection method according to claim 1, wherein there is a connection abnormality in which the upstream port and the downstream port of the target slave device are mistaken. A connection in a network system, which is composed of a master device and a plurality of slave devices, and data transmitted from the master device is returned to the master device after sequentially passing from the most upstream slave device to the most downstream slave device. An anomaly detection method,
Each slave device has a plurality of ports including an upstream port for connecting to an upstream device and at least one downstream port for connecting to a downstream device;
The connection abnormality detection method is:
The master device acquiring topology information that is a topology of the network system;
Based on the topology information, the master device is configured so that the target slave device to be inspected is the most downstream and the master device to the target slave device has a serial topology. A port control step for switching between blocking and opening; and
The master device transmitting inspection data after the port control step;
The master device detecting a connection abnormality of the target slave device based on a return status of the inspection data; and
Have
The topology information acquired by the master device in the acquiring step includes a position address determined based on the order in which each slave device is connected and the type of port used for connection between the slave devices,
The inspection data transmitted by the master device in the transmitting step is data for confirming the number of slave devices included in the serial topology formed in the port control step,
In the detecting step, the master device does not match an expected value of the number of devices to the target slave device obtained from the topology information and the position address and the number of devices confirmed by the returned inspection data. In this case, it is assumed that there is a connection abnormality that mistakes the upstream port and the downstream port of the target slave device.
A method for detecting connection abnormality. The network system is composed of a master device and a plurality of slave devices, and data transmitted from the master device is returned to the master device after sequentially passing from the most upstream slave device to the most downstream slave device. ,
Each slave device has a plurality of ports including an upstream port for connecting to an upstream device and at least one downstream port for connecting to a downstream device;
The master device is
Means for obtaining topology information which is a topology of the network system;
Based on the topology information, the port of each slave device is switched off and open so that the target slave device to be inspected is the most downstream and the topology from the master device to the target slave device is a serial topology. Port control means;
A transmission / reception means for transmitting the inspection data after the control by the port control means is performed, and receiving the inspection data returned;
Based on the return status of the inspection data, a determination unit that detects a connection abnormality of the target slave device;
Have
When the topology of the network system includes a branching location, the port control unit causes the master device to select one of the branch destinations to form a serial topology. . It consists of a master device and a plurality of slave devices, and the data transmitted from the master device is returned to the master device after sequentially passing from the most upstream slave device to the most downstream slave device, each slave device A master device in a network system having a plurality of ports including an upstream port for connecting to an upstream device and at least one downstream port for connecting to a downstream device,
Means for obtaining topology information which is a topology of the network system;
Based on the topology information, the port of each slave device is switched off and open so that the target slave device to be inspected is the most downstream and the topology from the master device to the target slave device is a serial topology. Port control means;
A transmission / reception means for transmitting the inspection data after the control by the port control means is performed, and receiving the inspection data returned;
Based on the return status of the inspection data, a determination unit that detects a connection abnormality of the target slave device;
Have
The master device , wherein when the topology of the network system includes a branch point, the port control unit selects one of branch destinations to form a serial topology . The network system is composed of a master device and a plurality of slave devices, and data transmitted from the master device is returned to the master device after sequentially passing from the most upstream slave device to the most downstream slave device. ,
Each slave device has a plurality of ports including an upstream port for connecting to an upstream device and at least one downstream port for connecting to a downstream device;
The master device is
Means for obtaining topology information which is a topology of the network system;
Based on the topology information, the port of each slave device is switched off and open so that the target slave device to be inspected is the most downstream and the topology from the master device to the target slave device is a serial topology. Port control means;
A transmission / reception means for transmitting the inspection data after the control by the port control means is performed, and receiving the inspection data returned;
Based on the return status of the inspection data, a determination unit that detects a connection abnormality of the target slave device;
Have
The topology information acquired by the master device by the acquiring means includes each slave device.
Position address determined based on the order in which devices are connected and the type of port used for connection between slave devices,
The inspection data transmitted by the master device by the transmission / reception means is data for confirming the number of slave devices included in the serial topology formed by the port control means,
When the determination unit determines that the master device does not match the expected number of devices up to the target slave device obtained from the topology information and the position address with the number of devices confirmed by the returned inspection data And there is a connection abnormality that mistakes the upstream port and the downstream port of the target slave device.
A network system characterized by this. It consists of a master device and a plurality of slave devices, and the data transmitted from the master device is returned to the master device after sequentially passing from the most upstream slave device to the most downstream slave device, each slave device A master device in a network system having a plurality of ports including an upstream port for connecting to an upstream device and at least one downstream port for connecting to a downstream device,
Means for obtaining topology information which is a topology of the network system;
Based on the topology information, the port of each slave device is switched off and open so that the target slave device to be inspected is the most downstream and the topology from the master device to the target slave device is a serial topology. Port control means;
A transmission / reception means for transmitting the inspection data after the control by the port control means is performed, and receiving the inspection data returned;
Based on the return status of the inspection data, a determination unit that detects a connection abnormality of the target slave device;
Have
The topology information acquired by the master device by the acquiring means includes a position address determined based on the order in which each slave device is connected and the type of port used for connection between the slave devices,
The inspection data transmitted by the master device by the transmission / reception means is data for confirming the number of slave devices included in the serial topology formed by the port control means,
When the determination unit determines that the master device does not match the expected number of devices up to the target slave device obtained from the topology information and the position address with the number of devices confirmed by the returned inspection data And there is a connection abnormality that mistakes the upstream port and the downstream port of the target slave device.
A master device characterized by that.

Images